In vitro Skin irritation

Dermal Irritation in 3D Human Tissue Constructs

TG 439

Skin irritation refers to the production of reversible damage to the skin following the application of a test chemical for uo to 4 hrs. (UN GHS) 3-D reconstructed human epidermal (RHE) tissue constructs are utilized in this organotypic in vitro model. Tissue viability is determined using the vital dye MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). The reduction of MTT in treated cultures is expressed as a percentage relative to untreated (negative control) cultures.

RHE tissue constructs are made from human epithelial cells, which are differentiate to form a fully differentiated epidermis and a complete functional stratum corneum.

This model allows test materials topical application, so solids, undiluted final formulations, and insoluble test materials can also be tested.

MTT, a vitality-indicating dye, is actively taken up by the tissues and subsequently reduced in the mitochondria of living cells. This chemical reaction produces a purple-colored compound (formazan) within the cells, causing the live tissues to turn deep purple in color. Chemical is identified as a irritant if it causes decrease in cell viability below 50 % threshold. The extent of reduction in MTT dye is thus used to indentify the skin irritation capacity of test chemical.